diff --git a/alib2std/src/extensions/tree_base.hpp b/alib2std/src/extensions/tree_base.hpp
index 5a7dcdf233f59f96b5246292afee2d45b56f5245..baa7b43bc741ad99b869f53d69895ed7060dea5c 100644
--- a/alib2std/src/extensions/tree_base.hpp
+++ b/alib2std/src/extensions/tree_base.hpp
@@ -37,7 +37,7 @@ class BaseNode {
 	}
 
 	const Data * operator ->( ) const {
-		return static_cast < Data * > ( this );
+		return static_cast < const Data * > ( this );
 	}
 
 public: